Portable air pollution detector

ABSTRACT

Method and apparatus for rapidly and accurately testing, in a laboratory or preferably a field location, a sample, preferably a gasoline sample, to determine olefins having up to a predetermined number of carbon atoms therein by first chromatographically separating the olefins having up to one more carbon atom than said predetermined number from the remainder of the olefins, secondly time separating the olefins having up to said predetermined number of carbon atoms from the chromatographically separated stream by switching off the stream after the olefins having a predetermined number of carbon atoms, but before the olefins having one more carbon atom than said predetermined number pass through a detector, and finally detecting the presence of the olefins in the time separated stream by use of a suitable means such as a bromine coulometric titrator.

Silas [451 Apr.4, 1972 [54] PORTABLE AIR POLLUTION DETECTOR [72]Inventor: Robert S. Silas, Bartlesville, Okla.

I [73] Assignee: Phillips Petroleum Company 22 Filed: June 5,1969

21 Appl.No.: 830,612

[52] U.S. Cl ..23/230 R, 23/232 C, 23/253 R, 55/67, 55/197, 55/386,73/23.], 204/195 [51] Int. Cl. ..B0lk 3/00, G0ln 31/08 [58] Field ofSearch ..23/230, 232 C, 253; 204/195 T; 55/67, 197, 386; 73/23.1

[56] References Cited UNITED STATES PATENTS I 3,030,280 4/1962 Miller..204/195 T X 3,111,835 11/1963 Jenkins ..23/232C OTHER PUBLICATIONSFisher Bulletin FS- 275, (1960).

Dal Nagare et al., Gas Liquid Chromatography, Interscience PubL, 1962,p. 234

- Pn'mary Examiner-Morris O. Wolk Assistant Examiner-R. M. ReeseAttorney-Young and Quigg [57] ABSTRACT Method and apparatus for rapidlyand accurately testing, in a laboratory or preferably a field location,a sample, preferably a gasoline sample, to determine olefins having upto a predetermined number of carbon atoms therein by firstchromatographically separating the olefins having up to one more carbonatom than said predetermined number from the remainder of the olefins,secondly time separating the olefins having up to said predeterminednumber of carbon atoms from the chromatographically separated stream byswitching off the stream after the olefins having a predetermined numberof carbon atoms, but before the olefins having one more carbon atom thansaid predetermined number pass through a detector, and finally detectingthe presence of the olefins in the time separated stream by use of asuitable means such as a bromine coulometric titrator.

l 1 Claims, 2 Drawing Figures Patented April 4, 1972 I 3,653,840

TIMER 55 FIG. L V

INVENTOR.

R. S. SILAS A T TOR/VEYS This invention relates to detection of olefinshaving up to a predetermined number of carbon atoms in a streamcontaining both olefins and nonolefins.

A method of measuring the concentration of constituents of a fluidstream often involves the use of a chromatographic analyzer. Inchromatography, vaporous sample material to be analyzed is introducedinto a column containing a selective sorbent or partitioning material. Acarrier gas is directed into the column so as to force the samplematerial therethrough. The selective sorbent, or partitioning material,attempts to hold the constituents of the mixture. This results in theseveral constituents of the fluid mixture flowing through the column atdifferent rates of speed, depending upon their affinities for thepacking material. The column effluent thus consists inithepredeterrnined number of carbon atoms and nonolet'ms is -then tested todetermine the quantity of olefins present tially of the carrier gasalone, the individual constituents of the fluid mixture appearing laterat spaced time intervals. A conventional method of detecting thepresence and concentration of these constituents is to employ a thermalconductivity detector which compares the thermal conductivity of theeffluent gas plus carrier gas with the thermal conductivity of thecarrier gas directed to the column. The resulting chromatographic peaksproduced by the detector are recorded on a chart with each peakrepresentative of a sample constituent.

In recent years great interest has been generated in controlling theproduction of smog and other air pollutants caused by the combustion ofhydrocarbons, particularly gasoline in combustion processes, and moreparticularly gasoline in internal combustion engines of automobiles.Several states have passed legislation directed to the grave problem ofair pollution by automobile engines and legislation has been consideredat the federal level.

Recent research in the area of air pollution from gasolines has revealedthat a large portion of the pollution caused by combustion of gasolinein automobiles results from light olefins, particularly C and lighterolefins, that exist in normal gasolines traveling through the engineuncombusted and exiting to the atmosphere along with the combustionproducts. Upon entering the atmosphere in a gaseous form lighter olefinsexhibit a tendency to combine very readily with various materials in theatmosphere, such as sulfur, oxygen, and halogens and produce airpollutants commonly know as smog". Generally, air pollution becomesacute when a gasoline contains in excess of 5 per cent by weight olefinsof C or lighter based on the weight of the gasoline.

Conventional methods for determination of olefins in a stream take aconsiderable amount of time, and must be conducted by highly skilledpersonnel in permanent laboratory installations. Examples of suchanalytical methods are fluorescent indicator absorption, massspectrometry, chemical methods (ASTM Method D-875) and conventionalchromatography.

In accordance with this invention, a rapid and accurate determination ofthe quantity of olefins having up to a predetermined number of carbonatoms, particularly C and lighter hydrocarbons, in a stream, andparticularly in gasoline, can be conducted by relatively nonskilledpersonnel in field locations by use of the portable device of thisinvention. Broadly, the practice of the invention compriseschromatographically separating in a chromatographic column olefinshaving up to one more carbon atom than a predetermined number of carbonatoms from the remainder of the olefins in a stream that contains botholefins and nonolefins. After the chromatographic separation, then theolefins having up to the therein, all of which are olefins having up tothe predetermined number of carbon atoms. In another embodiment, arestrictor column is operated in series with the chromatographic columnto reduce the time necessary for backflushing the chromatographiccolumns afier a test has been run by placing a greater backflushingpressure on the chromatographic column than the pressure used forchromatographic separation.

Accordingly, an object of my invention is to provide an improvedchromatographic method of analysis and apparatus therefor.

Another object of my invention is to provide an improved chromatographicmethod and apparatus wherein said analysis includes a chromatographiccolumn backflushing step.

Another object of my invention is to provide for improvedchromatographic analysis of olefins in a stream containing both olefinsand nonolefins.

Another object of my invention is to provide a portable apparatus fordetermining the quantity of olefins having up to a predetermined numberof carbon atoms in a stream containing olefins and nonolefms.

Another object of my invention is to provide a portable apparatus fordetermining the quantity of C and lighter olefins in a gasoline stream.

Another object of my invention is to decrease the time required forolefin determination.

Another object of my invention is to decrease the time necessary forbackflushing the chromatographic column after completing a test.

Another object of my invention is to provide olefin determination byrelatively unskilled personnel.

Other objects, advantages and features of my invention will be readilyapparent to those skilled in the art from the following description, thedrawings and the appended claims.

The attached figures represent only one embodiment of the invention asother embodiments will be readily apparent to one skilled in the art.Specifically,

FIG. 1 represents a schematic view of one embodiment of this invention.

FIG. 2 represents the invention in its portable form wherein it has beenmounted inside an enclosed structure which is adapted for handtransportation by the installation of handles thereon.

Referring now to the apparatus illustrated in FIG. 1, there is a sourceof carrier gas and a conduit from said carrier gas to a four-wayswitching valve means containing valve ports A, B, C and D. In line 15there is disposed a valve means so as to regulate the pressure of thecarrier gas going into the chromatographic system. A restrictor columnis connected to valve means 20 and four-way switching valve meanscontaining valve ports A, B and C is connected to column 30. Achromatographic separation column is attached to valve means 35 byconduit containing an injection port wherein the stream to be tested forthe existence of olefins is injected into the system. Chromatographiccolumn 40 is connected to valve means 20 via conduit and is furtherconnected by conduit to a means 60 to detect the presence of olet'ms.Four-way switching valve means 20 and 35 are operably connected totiming means 85 and adapted to switch from a testing position to abackflushing position on response to a given time that was set on timingmeans 85 elapsing. This operation will be subsequently explained indetail.

Detectors and are disposed in respective conduits l5 and 55. Thesedetectors are adapted to measure a property of the fluid sample mixturedirected thereto which property is representative of the composition ofthe fluid mixture. The detectors can be thermally conductive elementscalled thermistors which are temperature sensitive resistance elementsdisposed in the path of fluid flow. The temperature differences betweenthe resistance elements can be measured in detector cell by apparatusincluding electrical bridge circuits, such as a Wheatstone bridge, andprovide response to the temperature difference signals representative ofthe difference in thermal conductivity in the column of fluid in thecarrier gas.

Although thermistors are used as detectors in one embodiment, thedetectors can be any other type of apparatus known in the art formeasuring the property of a gaseous stream.

Restrictor column 30 is filled with a material that restricts thepassage of all components therethrough, thus creating a pressure dropbetween valve means 20 and 35 through said column 30. According to thisinvention, the column performs no chromatographic separation and doesnot function as a chromatographic column. The operation of this columnwill be described later.

Although this invention is fully applicable to separating from a streamolefins having up to a predetermined number of carbon atoms from achromatographically separated stream containing olefins having up to onemore carbon atom than name material sold by Johns Manville Corporationand is crushed fire brick. Dow-Corning Silicone-200 is a commerciallyavailable trade name material sold by Dow-Coming Corporation and is asilicone polymer incorporating methyl and phenyl groups. In oneembodiment, chromatographic column 40 was 3 feet long and constructed ofV4-inch O.D.

' copper tubing. The restrictor column in one embodiment was 4 feet longand was constructed of 54-inch O.D. copper tubing filled with 80 to 100mesh Chromasorb-P. 1

With reference to FIG. 2 there is noted an enclosed structure 200incorporating handles 205 and 210. Enclosed structure 200 isspecifically adapted in size to be hand transported by one or two mengrasping handles 205 and 210. Additionally, thereis indicated sampleinjection port 50, timer 85, and the starter button 215 for the means todetect the presence of olefins 60 which in this particular embodiment isa bromine coulometric titrator. Additionally, there is indicated thetimer 220 and the generation current selector 225 associated with thebromine titrator.

Prior to operation the invention can be calibrated to separate olefinshaving up to five carbon atoms by the following method. Valve means 25is adjusted to put the design pressure of carrier gas in the system. Thesample is then injected by means of a hypodermic syringe or othersuitable means into injection port 50 and the time of injection noted.The lighter components which comprise both olefin and nonolefincomponents begin to elute from column 40 and, subsequently, the

.olefins of C, through C, elute from column 40 along with othernonolefinic components. As noted in the drawing, when valve means 20 and35 are in testing position, the elution products from column 40 movethrough conduit 55 through ports D and C of valve means 20, throughconduit 65 and into detection means 60. The calibration is completed bymaking various 1 runs and determining the length of time necessary fromthe injection of the sample material in port.50 to the elapsed time thatthe last of the C olefins but before any of the C, olefins pass port Cof valve means 20. After this particular time is determinedexperimentally, it is noted and will be used in future operation ofthemachine in actual tests. Obviously, the same method can be used tocalibrate the invention to separate other olefins up to a predeterminednumber of carbon atoms.

In actual operation this predetermined time will be set in timer means85 and, after the elapsation of the predetermined time, timer means 85will actuate valve means and 35 to switch from a testing positionwherein gas is conducted through ports A and B of valve means 20,through column 30, through ports A and B of valve means 35, throughcolumn 40, through ports D and C of valve means 20, and through conduit65 to olefin detector 60 to a backflushing position wherein carrier gasis conducted through ports A and D of valve means 20 through column 40and through ports B and C of valve means 35 and to the atmosphere. Thus,after the elapsation of the time known to be associated with the passageof the last of the C, olefin through port C of valve means 20, thecolumn is backflushed by action of timer and valve means 20 and 35.

Quite obviously, the maximum elution time is associated with theheaviest" olefin having the predetermined number of carbon atoms whichin the embodiment where olefins having up to five carbon atoms areseparated is methyl- 2-butene. Although the time between elution of thelast of the C, and the first of the C olefins varies with manyparameters, in practice up to 20 seconds can elapse, thus time iscritical only within a fairly broad range of time.

Thus, according to the operation of the invention, after the inventionas been calibrated according to the previously described method actualtesting for the presence of C and lighter olefins can be conducted. Inthis test the carrier gas pressure is set in valve means 25 and carriergas is caused to flow from source 10 through valve ports A and B ofvalve means 20, restrictor column 30, .valve ports A and B of valvemeans 35, and through separator column 40. The predetermined time fromthe calibration method is set in timing means 85 and simultaneously asample of gasoline is injected into injection port 50. According to theoperation of the invention, the carrier gas transports the fluid sampleinjected into the injection port 50 through chromatographic separationcolumn 40 and through conduit 55, ports D and C of valve means 20, andsubsequently through conduit 65 to detector means 60.

According to the operation of chromatographic column 40, both olefin andnonolefin components are simultaneously eluted. Thus, the elutionproducts initially contain nonolefmic components plus lighter olefinsand subsequently heavier olefins are eluted along with heaviernonolefinic components. As noted earlier, at the time the sample wasinjected into injection port 50, timer 85 was set so as to switch valvemeans 20 and 35 at the end of the period determined by the calibrationfunction. After timer 85 runs down valve means 20 and 35 are switchedfrom the previously described testing position to the previouslydescribed backflushing position.

According to this invention, detector means 60 can comprise any means ofdetecting the presence of olefins and, according to one embodiment ofthis invention, the only olefins present in said stream containingolefins and nonolefins will be C olefins and lighter. Although manymeans to detect the presence of ole fms can be used, in one embodiment acoulometric bromine titrator was used. This titrator is described inASTM Method D-l492-60.

Thus, according to the embodiment of the invention where the brominecoulometric titrator is used, after injection of the sample into port 50but before the first C, olefin enters the coulometric titrator starterbutton 215 in FIG. 2 is depressed. According to ASTM Method D-l492-60current selector 225 is set according to the estimated bromine index andthe estimated sample weight. Depressing starter button 215 actuates thedevice so that timer 220 records the titration time. The coulometrictitrator can be adapted to shut down when the last olefin enters thedetector and has been titrated. Thus, according to this embodiment thebromine index is then calculated by knowing the current generation inmilliamperes set on current selector 225, the titration time in secondsread off timer 220, and the weight of the sample in grams.

According to another embodiment of this invention, a backflushingfunction is performed through the use of restrictor column 30 in FIG. 1.According to this feature of the invention, after the C but before theC, olefins pass port C of valve means 20 timer 85 actuates four-wayswitching valves 20 and 35 to the backflushing position so as to conductcarrier gas through ports A and D of valve means 20 through separationcolumn 40 in the opposite direction as during testing, through conduit45 and through ports B and C of valve means 35. In normal operation ofthe invention the carrier gas flows through restrictor column 30 andthrough chromatographic separation column 40, and after the pressuredrop across column 30 is known the pressure in valve 25 can be set so asto achieve the design pressure at the inlet of chromatographic column40. Thus, a first pressure drop occurs through restrictor column 30 anda second pressure drop occurs through chromatographic column 40. Thus,when timer 85 actuates the valves to a backflushing position, the higherpressure on the inlet of restrictor column 30, which is higher than theinlet pressure on chromatographic separation column 40 due to thepressure drop across column 30, is then placed through ports A and D ofvalve means 20 and through conduit 55 and causes carrier gas to flow inthe opposite direction through chromatographic separation column 40,conduit 45, and subsequently through ports B and C of valve means 35 tothe atmosphere. Thus, through the use of the additional pressure drop inrestrictor column 30 an additional pressure differential is developedthrough chromatographic column 40 flowing in the opposite direction andused for backflushing the column. This embodiment where the restrictorcolumn is used is an optional feature and it is fully within the scopeof this invention to eliminate the restrictor column and merely use thechromatographic column 40, although the chromatographic column 40 can bebackflushed much more rapidly according to the practice of the inventionwhere the restrictorcolumn 30 is used.

Thus, this invention is useful for determining the presence of olefinshaving from two to five carbon atoms in any stream whatsoever and isparticularly adapted for determining the quantity of olefins having fromtwo to five carbon atoms and,

in gasoline streams.

Thus, this invention is broadly applicable to determining the quantityof olefins having up to a predetermined number of carbon atoms in astream. As noted above, the drawing is merely diagrammatic and is notintended to fully show all component parts of the apparatus which oneskilled in the art would routinely design for the operation thereof.Indeed, the showing of an element or piece of equipment does not meanthat all such or similar pieces of equipment which may or can bedesigned by one skilled in the art in possession of the disclosurecannot be utilized as substitution therefor. Likewise, the omission ofan element which one skilled in the art may include in an actual unitdoes not mean that such a piece of equipment is intended to be omittedsimply because it does not appear in the drawing. Specifically, as notedrestrictor column 30 can be omitted; however, in one embodiment greaterbackflushing efficiency is obtained by its use. Furthermore, column 40can be packed with any material that will chromatographically separateolefins having up to one more carbon atom than said predetermined numberof carbon atoms. Additionally, the apparatus of this invention can bemounted in various types of enclosed housing for transportation. Sufficeto say the drawing is for illustrative purpose only as is thedescription thereof.

iclaim:

l. A method of detecting the presence of olefins having up to apredetermined number of carbon atoms in a stream comprising olefins andnonolefins comprising the steps of:

i. conducting a stream of inert carrier gas through a restrictor columnso as to establish a first pressure drop through said column;

ii. conducting said carrier gas stream through a separation zone in aforward direction;

iii. conducting said stream comprising olefins and nonolefins throughsaid separation zone in a forward direction;

iv. chromatographically separating in said separation zone said streamcomprising olefins and nonolefins to obtain an eluent stream comprisingolefins having up to a predetermined number of carbon atoms;

v. conducting said. eluent stream comprising olefins having up to apredetermined number of carbon atoms to an olefin detector zone during atime period selected so as to terminate after said eluent comprisingolefins having up to said predetermined number of carbon atoms hasentered said detector zone but before additional eluent from saidseparation zone, said additional eluent comprising olefins having onemore carbon atom than said predetermined number of carbon atoms, enterssaid detector zone;

vi. isolating said olefin detector zone and backflushing said separationzone by conducting said carrier gas through said separation zone in adirection opposite to the forward direction flow through said separationzone; and

. vii. detecting, in said olefin detector zone, by bromine titration thepresence or absence of olefins having up to said predetermined number ofcarbon atoms in said stream comprising olefins and nonolefins.

2. A method of detecting the presence of olefins having up to fivecarbon atoms in a stream comprising olefins and nonolefins comprisingthe steps of:

i. conducting a carrier gas through a restrictor column so as toestablish a first forward pressure drop through said column;

ii. conducting said carrier gas through a chromatographic separationzone in a forward direction;

iii. conducting said stream comprising olefins and nonolefins throughsaid separation zone in said forward direction;

iv. chromatographically separating in said separation zone said streamcomprising olefins and nonolefins to obtain an eluent stream comprisingolefins having up to six carbon atoms;

v. time separating from said eluent stream a stream comprising olefinshaving from two to five carbon atoms by conducting said streamcomprising olefins having up to five carbon atoms to an olefin detectorzone during a time period selected so as to terminate after said streamcomprising olefins having up to five carbon atoms has entered saiddetector zone but before said olefins having six carbon atoms enter saiddetector zone;

vi. backflushing said separation zone by conducting said carrier gasthrough said separation zone in a direction opposite to the forwarddirection flow through said column, said separation zone beingbackflushed faster by subjecting the separation zone to a greaterreverse pressure drop than said first forward pressure drop due to theuse of said restrictor column; and

vii. detecting, in said olefin detector zone, by bromine titration thepresence or absence of olefins having up to five carbon atoms in saidstream comprising olefins and nonolefins.

3. Apparatus comprising, in combination:

i. a chromatographic separation column;

ii. a source of inert carrier gas;

iii. an analyzer means to analyze chromatographically separated eluentfrom said chromatographic separation column, said analyzer means beingresponsive only to the presence of olefins in said eluent;

iv. first conduit means connecting said separation column and said inertcarrier gas source;

v. second conduit means connecting said separation column and saidanalyzer means; vi. means for introducing a sample to be analyzed intosaid separation column, said sample introduction means being positionedin said first conduit intermediate said separation column and saidcarrier gas source;

' first chromatographic detector positioned in said first conduit so asto detect a property of said carrier gas when said gas is flowing insaid conduit, said detector being responsive to said property andcapable of generating a signal in response thereto, said position beingintermediate said carrier gas source and said sample introduction means;

viii. second chromatographic detector positioned in said second conduitso as to detect a property of eluent from said separation column whensaid eluent is flowing in said conduit, said detector being responsiveto said property and capable of generating a signal in response thereto,said position being intermediate said separation'column and saidanalyzer means;

ix. a chromatographic detector cell operatively attached to said firstand second chromatographic detectors, said detector cell beingresponsive to signals generated by said first detector in response to aproperty of said carrier gas and by said second detector in response toa property of said eluent;

x. a first valve means, said first valve means having testing andbackflushing positions; said valve means being in communication withsaid first and second conduits; said valve means, when in testingposition, being adapted to permit said carrier gas to flow from saidsource through at least a portion of said first conduit, through saidvalve means, through at least another portion of said first conduit,through said separation column, through at least a portion of saidsecond conduit, through said valve means to said analyzer means; saidvalve means being further adapted, when in a backflushing position, topermit said carrier gas to flow through at least a portion of said firstconduit, through said valve means, through at least a portion of saidsecond conduit, through said separation column in the opposite directionas the carrier gas flow while in the testing position; said valve means,when in a backflushing position, being further adapted to prevent theflow of carrier gas through said analyzer means; and

xi. a timing means operatively connected to said first valve means forcontrolling the operation thereof to provide spaced periods of testingoperation during spaced intervals of time and spaced periods ofbackflushing operation during spaced intervals of time.

4. The apparatus of claim 3 further comprising:

i. a restrictor column positioned within said first conduit,

said column being positioned intermediate said first chromatographicdetector and said sample introduction means;

ii. a second valve means positioned in said first conduit intermediatesaid restrictor column and said chromatographic separation column; saidsecond valve means having testing and backflushing positions; saidsecond valve means being adapted, when in a testing position, tocommunicate carrier gas from said carrier gas source through said firstconduit to said separation column; said second valve means being furtheradapted, when in a backflushing position, to communicate carrier gasthrough said separation column in the opposite direction as the carriergas flow while in the testing position through said second valve means;

iii. wherein said timing means is operatively attached to said first andsecond valve means for controlling the operation thereof to providespaced periods of testing operation during spaced intervals of time andspaced periods of backflushing operation during spaced intervals oftime; and

iv. wherein said analyzer means comprises a bromine coulometrictitrator.

5. The apparatus of claim 4 mounted on a frame structure adapted to betransported by hand, said frame structure being substantially enclosed.

6. The apparatus of claim 3 mounted on a frame structure adapted to betransported by hand.

7. The apparatus of claim 6 wherein said frame structure issubstantially enclosed.

8. Apparatus comprising, in combination:

a. means to chromatographically separate olefins having up to one morecarbon atom than a predetermined number of carbon atoms from a streamcomprising olefins and nonolefins;

b. means to introduce said stream comprising olefins and nonolefins intosaid chromatographic separation means; c. a timing means adapted to timeseparate olefins havingup to said predetermined number of carbon atomsfrom a chromatographically separated stream from said chromatographicseparation means containing nonolefins and olefins having up to one morecarbon atom than said predetermined number of carbon atoms; and

d. a detector means communicating with said chromatographic separationmeans for detecting the presence of olefins only in said streamcontaining nonolefins and olefins having up to said predetermined numberof carbon atoms; wherein said chromatographic separation meanscomprises:

i. a source of inert carrier gas;

ii. a chromatographic separation column;

iii. a first conduit in communication with said source of carrier gasand said chromatographic separation column;

iv. a first restrictor column positioned within said first conduit;

v. a second conduit in communication with said chromatographicseparation column and said olefin detector means;

vi. a first chromatographic detector positioned within said firstconduit so as to contact said source of carrier gas;

vii. a second chromatographic detector positioned within said secondconduit so as to contact chromatographically separated eluent from saidchromatographic separation column;

viii. a detector cell operably attached to said first and secondchromatographic detectors;

ix. a first valve means operably connected to said first and secondconduits, said valve means being positioned in said first conduitupstream from said restrictor column sand in said second conduitdownstream from said chromatographic separation column;

x. a second valve means positioned in said first conduit upstream fromsaid chromatographic separation column and downstream from saidrestrictor column;

said first and second valve means having testing and backflushingpositions; said first and second valve means being adapted to, when in atesting position, to communicate carrier gas via said first conduit fromsaid source of carrier gas, through said first valve, through saidrestrictor column, through said second valve means, to saidchromatographic separation column, and eluent from said separationcolumn, via said second conduit, through said first valve means to saidolefin detector means; said first and second valve means being furtheradapted, when in a backflushing position, to communicate carrier gas viasaid first conduit through said first valve means and, via

said second conduit, through said separation column in a directionopposite to the flow through said column when in a testing position and,via said first conduit, through said second valve means; said firstvalve means being further adapted, when in a backflushing position, toprevent communication of carrier gas through said second conduit to saidolefin detector means;

wherein said timing means comprises a timer operably attached to saidfirst and second valve means, said timer being adapted to switch from atesting position to a backflushing position after said eluent comprisingup to C, olefins has passed said first valve means but before saideluent containing C olefins passes said first valve means; and

wherein said olefin detector means comprises a bromine coulometrictitrator. 9. The apparatus of claim 8 mounted on a frame structureadapted to be transported by hand.

10. The apparatus of claim 9 wherein said frame structure issubstantially enclosed.

l 1. The apparatus of claim 10 wherein said substantially enclosed framestructure contains handles adapted to provide a hand portable characterto said structure.

I I! i I

2. A method of detecting the presence of olefins having up to fivecarbon atoms in a stream comprising olefins and nonolefins comprisingthe steps of: i. conducting a carrier gas through a restrictor column soas to establish a first forward pressure drop through said column; ii.conducting said carrier gas through a chromatographic separation zone ina forward direction; iiI. conducting said stream comprising olefins andnonolefins through said separation zone in said forward direction; iv.chromatographically separating in said separation zone said streamcomprising olefins and nonolefins to obtain an eluent stream comprisingolefins having up to six carbon atoms; v. time separating from saideluent stream a stream comprising olefins having from two to five carbonatoms by conducting said stream comprising olefins having up to fivecarbon atoms to an olefin detector zone during a time period selected soas to terminate after said stream comprising olefins having up to fivecarbon atoms has entered said detector zone but before said olefinshaving six carbon atoms enter said detector zone; vi. backflushing saidseparation zone by conducting said carrier gas through said separationzone in a direction opposite to the forward direction flow through saidcolumn, said separation zone being backflushed faster by subjecting theseparation zone to a greater reverse pressure drop than said firstforward pressure drop due to the use of said restrictor column; and vii.detecting, in said olefin detector zone, by bromine titration thepresence or absence of olefins having up to five carbon atoms in saidstream comprising olefins and nonolefins.
 3. Apparatus comprising, incombination: i. a chromatographic separation column; ii. a source ofinert carrier gas; iii. an analyzer means to analyze chromatographicallyseparated eluent from said chromatographic separation column, saidanalyzer means being responsive only to the presence of olefins in saideluent; iv. first conduit means connecting said separation column andsaid inert carrier gas source; v. second conduit means connecting saidseparation column and said analyzer means; vi. means for introducing asample to be analyzed into said separation column, said sampleintroduction means being positioned in said first conduit intermediatesaid separation column and said carrier gas source; vii. firstchromatographic detector positioned in said first conduit so as todetect a property of said carrier gas when said gas is flowing in saidconduit, said detector being responsive to said property and capable ofgenerating a signal in response thereto, said position beingintermediate said carrier gas source and said sample introduction means;viii. second chromatographic detector positioned in said second conduitso as to detect a property of eluent from said separation column whensaid eluent is flowing in said conduit, said detector being responsiveto said property and capable of generating a signal in response thereto,said position being intermediate said separation column and saidanalyzer means; ix. a chromatographic detector cell operatively attachedto said first and second chromatographic detectors, said detector cellbeing responsive to signals generated by said first detector in responseto a property of said carrier gas and by said second detector inresponse to a property of said eluent; x. a first valve means, saidfirst valve means having testing and backflushing positions; said valvemeans being in communication with said first and second conduits; saidvalve means, when in testing position, being adapted to permit saidcarrier gas to flow from said source through at least a portion of saidfirst conduit, through said valve means, through at least anotherportion of said first conduit, through said separation column, throughat least a portion of said second conduit, through said valve means tosaid analyzer means; said valve means being further adapted, when in abackflushing position, to permit said carrier gas to flow through atleast a portion of said first conduit, through said valve means, throughat least a portion of said second conduit, through said separationcolumn in the opposite direction as the carrier gas flow while in thetesting position; said valve means, when in a backflushing position,being further adaPted to prevent the flow of carrier gas through saidanalyzer means; and xi. a timing means operatively connected to saidfirst valve means for controlling the operation thereof to providespaced periods of testing operation during spaced intervals of time andspaced periods of backflushing operation during spaced intervals oftime.
 4. The apparatus of claim 3 further comprising: i. a restrictorcolumn positioned within said first conduit, said column beingpositioned intermediate said first chromatographic detector and saidsample introduction means; ii. a second valve means positioned in saidfirst conduit intermediate said restrictor column and saidchromatographic separation column; said second valve means havingtesting and backflushing positions; said second valve means beingadapted, when in a testing position, to communicate carrier gas fromsaid carrier gas source through said first conduit to said separationcolumn; said second valve means being further adapted, when in abackflushing position, to communicate carrier gas through saidseparation column in the opposite direction as the carrier gas flowwhile in the testing position through said second valve means; iii.wherein said timing means is operatively attached to said first andsecond valve means for controlling the operation thereof to providespaced periods of testing operation during spaced intervals of time andspaced periods of backflushing operation during spaced intervals oftime; and iv. wherein said analyzer means comprises a brominecoulometric titrator.
 5. The apparatus of claim 4 mounted on a framestructure adapted to be transported by hand, said frame structure beingsubstantially enclosed.
 6. The apparatus of claim 3 mounted on a framestructure adapted to be transported by hand.
 7. The apparatus of claim 6wherein said frame structure is substantially enclosed.
 8. Apparatuscomprising, in combination: a. means to chromatographically separateolefins having up to one more carbon atom than a predetermined number ofcarbon atoms from a stream comprising olefins and nonolefins; b. meansto introduce said stream comprising olefins and nonolefins into saidchromatographic separation means; c. a timing means adapted to timeseparate olefins having up to said predetermined number of carbon atomsfrom a chromatographically separated stream from said chromatographicseparation means containing nonolefins and olefins having up to one morecarbon atom than said predetermined number of carbon atoms; and d. adetector means communicating with said chromatographic separation meansfor detecting the presence of olefins only in said stream containingnonolefins and olefins having up to said predetermined number of carbonatoms; wherein said chromatographic separation means comprises: i. asource of inert carrier gas; ii. a chromatographic separation column;iii. a first conduit in communication with said source of carrier gasand said chromatographic separation column; iv. a first restrictorcolumn positioned within said first conduit; v. a second conduit incommunication with said chromatographic separation column and saidolefin detector means; vi. a first chromatographic detector positionedwithin said first conduit so as to contact said source of carrier gas;vii. a second chromatographic detector positioned within said secondconduit so as to contact chromatographically separated eluent from saidchromatographic separation column; viii. a detector cell operablyattached to said first and second chromatographic detectors; ix. a firstvalve means operably connected to said first and second conduits, saidvalve means being positioned in said first conduit upstream from saidrestrictor column sand in said second conduit downstream from saidchromatographic separation column; x. a second valve means positioned insaid first conduit upstream from said chromatographic separation columnand downstream from said Restrictor column; said first and second valvemeans having testing and backflushing positions; said first and secondvalve means being adapted to, when in a testing position, to communicatecarrier gas via said first conduit from said source of carrier gas,through said first valve, through said restrictor column, through saidsecond valve means, to said chromatographic separation column, andeluent from said separation column, via said second conduit, throughsaid first valve means to said olefin detector means; said first andsecond valve means being further adapted, when in a backflushingposition, to communicate carrier gas via said first conduit through saidfirst valve means and, via said second conduit, through said separationcolumn in a direction opposite to the flow through said column when in atesting position and, via said first conduit, through said second valvemeans; said first valve means being further adapted, when in abackflushing position, to prevent communication of carrier gas throughsaid second conduit to said olefin detector means; wherein said timingmeans comprises a timer operably attached to said first and second valvemeans, said timer being adapted to switch from a testing position to abackflushing position after said eluent comprising up to C5 olefins haspassed said first valve means but before said eluent containing C6olefins passes said first valve means; and wherein said olefin detectormeans comprises a bromine coulometric titrator.
 9. The apparatus ofclaim 8 mounted on a frame structure adapted to be transported by hand.10. The apparatus of claim 9 wherein said frame structure issubstantially enclosed.
 11. The apparatus of claim 10 wherein saidsubstantially enclosed frame structure contains handles adapted toprovide a hand portable character to said structure.